Partially separated fiber bundle, production method of partially separated fiber bundle, fiber-reinforced resin molding material using partially separated fiber bundle, and production method of fiber-reinforced resin molding material using partially separated fiber bundle

ABSTRACT

A partially separated fiber bundle includes separation-processed sections and not-separation-processed sections that are alternately formed along the lengthwise direction of a fiber bundle that includes a plurality of single fibers, wherein the separation-processed sections include a plurality of divided fiber bundles that have been divided by separation processing. The partially separated fiber bundle is characterized in that the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform.

TECHNICAL FIELD

This disclosure relates to a partially separated fiber bundle and a method of producing the same and, more specifically, to a partially separated fiber bundle that enables continuous separation of a fiber bundle into a desired form without causing yarn breakage with respect to an inexpensive large tow having a large number of single fibers that is not expected with separation and, in particular, that can be formed into an optimum form to produce a molding material used for molding a composite material, a method of producing the same, and a fiber-reinforced resin molding material impregnated with resin after matting the partially separated fiber bundle, and a production method thereof comprising a series of steps until the material is manufactured.

BACKGROUND

A technology that produces a molded article having a desired shape is known in which a molding material comprising a bundle-like aggregate of discontinuous reinforcing fibers (for example, carbon fibers) (hereinafter, also referred to as a fiber bundle) and a matrix resin is used and it is molded by heating and pressurizing. In such a molding material, a molding material comprising a fiber bundle having a large number of single fibers is excellent in flowability at the time of molding, but tends to be inferior in mechanical properties of a molded article. On the other hand, a fiber bundle adjusted to an arbitrary number of single fibers is used as a fiber bundle in the molding material, aiming to satisfy both the flowability at the time of molding and the mechanical properties of the molded article.

As a method of adjusting the number of single fibers of the fiber bundle, for example, JP 2002-255448 A and JP 2004-100132 A disclose methods of performing a separation processing using a plurality of fiber bundle winding bodies prepared by winding a plurality of fiber bundles in advance. In those methods, however, because the number of single fibers of each fiber bundle treated in advance is restricted, the adjustment range is limited and, therefore, it is difficult to adjust to a desired number of single fibers.

Further, for example, JP 2013-49208 A, JP 2014-30913 A and Japanese Patent No. 5512908 disclose methods of longitudinally slitting a fiber bundle to a desired number of single fibers by using disk-shaped rotary blades. In those methods, although it is possible to adjust the number of single fibers by changing the pitch of the rotary blades, since the fiber bundle longitudinally slit over the entire length in the lengthwise direction has no convergence property, the yarn after the longitudinal slit tends to become difficult in handling such as winding it on a bobbin or unwinding the fiber bundle from the bobbin. In addition, when conveying the fiber bundle after the longitudinal slitting, the split end-like fiber bundle generated by the longitudinal slit may be wrapped around a guide roll, a feed roll or the like, which may not be easy to convey.

Further, WO 2012/105080 discloses a method of cutting a fiber bundle to a predetermined length at the same time as a longitudinal slit by a separation cutter having a lateral blade perpendicular to the fiber direction in addition to a longitudinal blade having a longitudinal slit function in a direction parallel to the fiber direction. According to that method, it becomes unnecessary to once wind the fiber bundle after the longitudinal slit to the bobbin and transport it, and the handling property is improved. However, since the separation cutter has the longitudinal blade and the lateral blade, when one of the blades reaches the cutting life first, an obstacle arises that the entire blade has to be exchanged.

Further, for example, JP 2011-241494 A and U.S. Patent Publication No. 2012/0213997 A1 describe a method in which a roll having a plurality of projections is provided on the outer circumferential surface of the roll, and the projections of the roll are pushed into a fiber bundle to partially separate the fiber bundle. In that method, however, because the circumferential speed of the roll and the conveying speed of the fiber bundle are basically the same speed synchronized with each other, it is impossible to control the lengths and the like of the separated-processed section and the not-separated-processed section, and it is difficult to obtain a partially separated fiber bundle with an optimum form.

Furthermore, EP 2 687 356 A1 describes a special method of forming intermittently extending flow paths for facilitating resin impregnation in a fiber bundle by a monofilament extending in a direction orthogonal to the fiber bundle. However, that manner relates to a technology of forming a flow path to facilitate resin impregnation in a fiber bundle and, therefore, it is basically a technology different from separation of a fiber bundle such as large tow.

As described above, to satisfy both the flowability during molding and the mechanical properties of a molded article, a fiber bundle adjusted to an arbitrary optimum number of single fibers is required.

Furthermore, in passing through the above-described longitudinal slitting process at a state where a fiber bundle is twisted such as twist exists in the fiber bundle itself or twist occurs during traveling of the fiber bundle at the separation step, because crossing fiber bundles are cut in the lengthwise direction, a problem occurs in that the fiber bundle is cut at a small length before and after the longitudinal slitting process and the longitudinal slitting cannot be continuously performed.

Accordingly, it could be helpful to provide a partially separated fiber bundle capable of forming a fiber bundle with an optimum number of single fibers to manufacture a molding material used for molding a composite material, and a method of producing a partially separated fiber bundle capable of slitting continuously and stably into the optimum fiber bundle formation. In particular, it could be helpful to provide a partially separated fiber bundle capable of controlling to an optimal distribution state of thin fiber bundles and thick fiber bundles when cutting/spraying the partially separated fiber bundle and preparing an intermediate base material of fiber bundles of discontinuous fibers to manufacture a molding material used for molding a composite material, thereby exhibiting the flowability during molding and the mechanical properties of a molded article at a good balance, and a method of producing the same. Furthermore, it could be helpful to provide a partially separated fiber bundle and a method of producing the same, enabling a continuous slitting without concern about the exchange life of a rotary blade even in a fiber bundle including twist or a fiber bundle of a large tow having a large number of single fibers.

Further, it could be helpful to provide a fiber-reinforced resin molding material in which the above-described partially separated fiber bundle is matted and impregnated with a resin, and a method of producing a fiber-reinforced resin molding material having a series of steps up to manufacture it.

SUMMARY

We thus provide:

(1) A partially separated fiber bundle in which separation-processed sections and not-separation-processed sections are alternately formed along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed sections being divided into a plurality of divided fiber bundles, the partially separated fiber bundle being characterized in that the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform. (2) The partially separated fiber bundle according to (1), wherein the numbers of single fibers of the divided fiber bundles are nonuniform in a width direction of the fiber bundle. (3) The partially separated fiber bundle according to (1) or (2), wherein the numbers of single fibers of the divided fiber bundles are nonuniform in the lengthwise direction of the fiber bundle. (4) The partially separated fiber bundle according to any one of (1) to (3), wherein the length of each of the separation-processed sections is 30 mm or more and 1,500 mm or less. (5) The partially separated fiber bundle according to any one of (1) to (4), wherein the length of each of the not-separation-processed sections is 1 mm or more and 150 mm or less. (6) The partially separated fiber bundle according to any one of (1) to (5), wherein the content of the not-separated-processed sections contained in the partially separated fiber bundle is 3% or more and 50% or less. (7) A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers is traveled along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a separation means in which the intervals of the projected parts are nonuniform in the width direction of the fiber bundle is penetrated, and separation processing is performed in a nonuniform manner with respect to the width direction of the fiber bundle. (8) A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers is traveled along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a plurality of separation means having different intervals of the projected parts are penetrated in order in the lengthwise direction of the fiber bundle, and separation processing is performed in a nonuniform manner with respect to the lengthwise direction of the fiber bundle. (9) A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers is traveled along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that the separation means is penetrated while the width of the fiber bundle is varied, and separation processing is performed in a nonuniform manner with respect to the lengthwise direction of the fiber bundle. (10) The method of producing a partially separated fiber bundle according to (9), wherein the nonuniform separation processing with respect to the lengthwise direction of the fiber bundle is performed together with the nonuniform separation processing according to (7) or (8). (11) The method of producing a partially separated fiber bundle according to any one of (7) to (10), wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, and the separation means is removed from the fiber bundle accompanying an increase of the pressing force. (12) The method of producing a partially separated fiber bundle according to any one of (7) to (11), wherein the presence of a twist of the fiber bundle in a range of 10 to 1,000 mm from the separation means having been penetrated into the fiber bundle in at least one of the front and rear of the fiber bundle along the lengthwise direction of the fiber bundle is detected by an imaging means. (13) The method of producing a partially separated fiber bundle according to (12), wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, a twist is detected by the imaging means, and the separation means is controlled so that the pressing force is reduced until the projected parts are passed through the twist from immediately before being contacted with the twist. (14) The method of producing a partially separated fiber bundle according to any one of (7) to (13), wherein a plurality of the projected parts are independently controllable. (15) The method of producing a partially separated fiber bundle according to any one of (7) to (14), wherein the separation means has a rotational shaft orthogonal to the lengthwise direction of the fiber bundle, and the projected parts are provided on a surface of the rotational shaft. (16) A fiber-reinforced resin molding material comprising a reinforcing fiber mat obtained by cutting/spraying the partially separated fiber bundle according to any one of (1) to (6) and a matrix resin. (17) The fiber-reinforced resin molding material according to (16), wherein the matrix resin is a thermosetting resin. (18) The fiber-reinforced resin molding material according to (16) or (17), wherein the fiber-reinforced resin molding material is a sheet molding compound. (19) A method of producing a fiber-reinforced resin molding material according to any one of (16) to (18), comprising at least the following steps [A] to [C]: [A] a partial separation step of obtaining a partially separated fiber bundle by alternately forming separation-processed parts and not-separation-processed parts along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed parts being separated so that the numbers of single fibers of divided fiber bundles in a separation-processed section are nonuniform; [B] a matting step of cutting the partially separated fiber bundle and spraying the cut bundles to obtain a reinforcing fiber mat; and [C] a resin impregnation step of impregnating a matrix resin into the reinforcing fiber mat. (20) The method of producing a fiber-reinforced resin molding material according to (19), wherein at least the steps [A] to [C] are carried out continuously in a single process. (21) The method of producing a fiber-reinforced resin molding material according to (19) or (20), wherein in the step [B], the partially separated fiber bundle is cut at an angle θ (0<θ<90°) with respect to the lengthwise direction thereof.

In the partially separated fiber bundle, since the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform, namely, since the partially separated fiber bundle is separated into comparatively thin bundles and comparatively thick bundles that have different numbers of single fibers, when the partially separated fiber bundle is cut and the cut bundles are sprayed to prepare an intermediate base material of fiber bundles of discontinuous fibers to manufacture a molding material used for molding a composite material, it becomes possible to control the thin fiber bundles and thick fiber bundles that have different numbers of single fibers at an optimal distribution state, and it becomes possible to exhibit the flowability during molding and the mechanical properties of a molded article at a good balance.

Further, in the method of producing a partially separated fiber bundle, the fiber bundle can be continuously and stably slit, and the partially separated fiber bundle with the above-described optimum form can be produced easily and efficiently. In particular, even in a fiber bundle containing twist or a fiber bundle of a large tow with a large number of single fibers, it is possible to provide a method of producing a partially separated fiber bundle, enabling a continuous slit processing without worrying about the exchange life of a rotary blade. Furthermore, it becomes possible to process a continuous slitting of an inexpensive large tow, and it becomes possible to reduce the material cost and the production cost of a molded article.

Further, in the fiber-reinforced resin molding material, because of containing a reinforcing fiber mat obtained by cutting and spraying the above-described partially separated fiber bundle capable of exhibiting the flowability during molding and the mechanical properties of a molded article at a good balance, and a matrix resin, also in molding thin fiber bundles and thick fiber bundles can be mixed at an optimal ratio, securely the flowability during molding and the mechanical properties of a molded article can be exhibited at a good balance.

Furthermore, in the method of producing a fiber-reinforced resin molding material, since a partially separated fiber bundle is manufactured by alternately forming separation-processed parts separated into a plurality of bundles and not-separation-processed parts, the partially separated fiber bundle is cut and sprayed to prepare a mat originating from the partially separated fiber bundle, and a matrix resin is impregnated thereinto to obtain the fiber-reinforced resin molding material, when the partially separated fiber bundle is cut and the cut bundles are sprayed to prepare an intermediate base material of fiber bundles of discontinuous fibers, it becomes possible to mix thin fiber bundles and thick fiber bundles at an optimal ratio, and it becomes possible to exhibit the flowability during molding and the mechanical properties of a molded article at a good balance. In particular, in the step of manufacturing the partially separated fiber bundle, as described above, it is possible to slit the fiber bundle continuously and stably, and it is possible to easily and efficiently produce the partially separated fiber bundle having an optimal form. Especially, even in a fiber bundle containing twist or a fiber bundle of a large tow with a large number of single fibers, continuous slit processing becomes possible without worrying about the exchange life of a rotary blade. Furthermore, it becomes possible to process a continuous slitting of an inexpensive large tow, thereby reducing the material cost and the production cost of a molded article. Further, in the method of producing a fiber-reinforced resin molding material, it becomes possible to perform a series of steps [A] to [C] continuously in a single process, and a desired fiber-reinforced resin molding material can be produced efficiently and smoothly, in addition, with an excellent productivity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing an example of a partially separated fiber bundle performed with separation processing to a fiber bundle (a nonuniform example in the width direction of a fiber bundle).

FIG. 2 is a schematic plan view showing another example of a partially separated fiber bundle performed with separation processing to a fiber bundle (a nonuniform example in the lengthwise direction of a fiber bundle).

FIGS. 3(A) and 3(B) show (A) a schematic plan view and (B) a schematic side view, showing an example of an operation in which a separation means is penetrated into a traveling fiber bundle.

FIGS. 4(A) and 4(B) show (A) a schematic plan view and (B) a schematic side view, showing an example of a movement cycle in which a moving separation means is penetrated into a fiber bundle.

FIGS. 5(A) and 5(B) show schematic explanatory views showing another example of a movement cycle in which a moving separation means is penetrated into a fiber bundle.

FIGS. 6(A) and 6(B) show (A) a schematic plan view and (B) a schematic perspective view, showing an example of a method of manufacturing a partially separated fiber bundle performed with a separation processing nonuniform in the width direction of a fiber bundle equivalent to that shown in FIG. 1.

FIGS. 7(A) and 7(B) show (A) a schematic plan view and (B) a schematic perspective view, showing an example of a method of manufacturing a partially separated fiber bundle performed with a separation processing nonuniform in the lengthwise direction of a fiber bundle equivalent to that shown in FIG. 2.

FIGS. 8(A) and 8(B) show (A) a schematic plan view and (B) a schematic perspective view, showing an example of a method of manufacturing a partially separated fiber bundle performed with a separation processing in a nonuniform manner while changing the width of a fiber bundle.

FIGS. 9(A) and 9(B) show explanation diagrams showing examples of rotating separation means for performing separation processing in nonuniform manners in a fiber bundle, (A) shows an example of a rotating separation means for performing a separation processing in a nonuniform manner in the width direction of a fiber bundle, and (B) shows an example of a rotating separation means for performing a separation processing in a nonuniform manner in the lengthwise direction of a fiber bundle.

FIG. 10 is a schematic diagram showing a method of producing a fiber-reinforced resin molding material according to an example.

FIG. 11 is a schematic perspective view showing an example of obliquely cutting a partially separated fiber bundle with respect to its lengthwise direction.

EXPLANATION OF SYMBOLS

-   -   1: process for producing fiber-reinforced resin molding material     -   2: partial separation step [A]     -   3: matting step [B]     -   4: resin impregnation step [C]     -   5: creel     -   6: reinforcing fiber bundle     -   6 a: reinforcing fibers     -   7: partially separated fiber bundle     -   8: cutter unit     -   8 a: cutting blade     -   9: spraying mechanism     -   10: reinforcing fiber mat     -   11: thermosetting resin     -   12: film     -   13: belt     -   14: resin impregnation roller     -   15: fiber-reinforced resin molding material     -   100: fiber bundle     -   110, 110 a, 110 b, 110 c: separation-processed section     -   120: not-separation-processed section     -   130, 130A, 130B, 130C, 140: partially separated fiber bundle     -   150: separation-processed part     -   160: not-separation-processed part     -   170: entanglement accumulation part     -   180: fluff accumulation     -   190: entangled part     -   200, 200A, 200C, 200 a, 200 b: separation means     -   210: projected part     -   210 a, 210 b: projected part plate     -   211: contact part     -   220A, 220B: rotating separation means     -   240: rotating shaft     -   300: fiber bundle width control device

DETAILED DESCRIPTION

Hereinafter, examples will be explained referring to the figures. This disclosure is not limited in any way to the examples in the drawings.

FIG. 1 shows an example of a partially separated fiber bundle performed with a separation processing to a fiber bundle, and shows an example of a partially separated fiber bundle performed with a separation processing nonuniform in the width direction of the fiber bundle. FIG. 2 shows an example of a partially separated fiber bundle performed with a separation processing nonuniform in the lengthwise direction of a fiber bundle. In FIGS. 1 and 2, symbol 100 denotes a fiber bundle comprising a plurality of single fibers, and along the lengthwise direction of the fiber bundle 100, separation-processed sections 110, 110 a, 110 b and 110 c each divided into a plurality of divided fiber bundles by a separation processing, and not-separation-processed sections 120, are alternately formed to manufacture partially separated fiber bundles 130, 140. Then, the separation processing is performed so that the numbers of single fibers of the divided fiber bundles in the separation-processed sections 110, 110 a, 110 b and 110 c become nonuniform.

In the partially separated fiber bundle 130 shown in FIG. 1, in each separation-processed section 110, it is separated in a nonuniform manner in the width direction of the fiber bundle 100 to be divided into divided fiber bundles having the numbers of single fibers different from each other (divided fiber bundle a, divided fiber bundle b, and divided fiber bundle c). In the partially separated fiber bundle 140 shown in FIG. 2, it is separated in a nonuniform manner in the lengthwise direction of the fiber bundle 100 to be divided into divided fiber bundles having the numbers of single fibers different from each other (divided fiber bundle a, divided fiber bundle b, and divided fiber bundle c) and, more specifically, in the separation-processed section 110 a, the fiber bundle 100 is separated to be divided into a plurality of divided fiber bundles a, and in the next separation-processed section 110 b, the fiber bundle 100 is separated to be divided into a plurality of divided fiber bundles b, and in the further next separation-processed section 110 c, the fiber bundle 100 is separated to be divided into a plurality of divided fiber bundles c. In FIGS. 1 and 2, symbol 150 denotes a separation-processed part, symbol 160 denotes a not-separation-processed part, symbol 170 denotes an entanglement accumulation part, and symbol 180 denotes fluff accumulation.

Next, the separation processing for the fiber bundle 100 will be explained. FIGS. 3(A) and 3(B) show (A) a schematic plan view and (B) a schematic side view, showing an example in which a separation means is penetrated into the traveling fiber bundle 100. In the figures, a fiber bundle running direction A (arrow) is the lengthwise direction of the fiber bundle 100, which shows that the fiber bundle 100 is continuously supplied from a fiber bundle supply device (not shown).

A separation means 200 is provided with a projected part 210 having a projecting shape which is easy to be penetrated into the fiber bundle 100, and which is penetrated into the traveling fiber bundle 100 to create a separation-processed part 150 approximately parallel to the lengthwise direction of the fiber bundle 100. It is preferred that the separation means 200 is penetrated in a direction along the side surface of the fiber bundle 100. The side surface of the fiber bundle means a surface in the vertical direction in a sectional end when the section of the fiber bundle is a flat shape such as a laterally elongated elliptical shape or a laterally elongated rectangular shape (for example, corresponding to the side surface of the fiber bundle 100 shown in FIGS. 3(A) and 3(B)). Further, the number of projected parts 210 to be provided may be one for each single separation means 200 or may be plural. When there are a plurality of projected parts 210 in one separation means 200, because the abrasion frequency of the projected part 210 decreases, it becomes possible to reduce the frequency of exchange. Furthermore, it is also possible to simultaneously use a plurality of separation means 200 depending upon the number of fiber bundles to be separated. It is possible to arbitrarily dispose a plurality of projected parts 210 by arranging a plurality of separation means 200 in parallel, staggeringly, in shifted phases or the like.

When the fiber bundle 100 comprising a plurality of single fibers is divided into separated bundles with a smaller number of fibers by the separation means 200, since the plurality of single fibers are substantially not aligned in the fiber bundle 100 but there are many portions interlaced at the single fiber level, entangled parts 190, in which the single fibers are interlaced in the vicinity of the contact parts 211 (in the vicinity of the portion A in FIG. 3(A)) during the separation processing, may be formed.

“Forming the entangled part 190” means, for example, forming (moving) the entanglement of single fibers with each other, which has been previously present in the separation-processed section, on the contact part 211 by the separation means 200, forming (producing) an aggregate, in which single fibers are newly interlaced, by the separation means 200 and the like.

After creating the separation-processed part 150 in an arbitrary range, the separation means 200 is removed from the fiber bundle 100. By this removal, a separation-processed section 110 performed with separation processing is created, and at the same time as that, the entangled parts 190 created as described above are accumulated in the end portion of the separation-processed section 110, and an entanglement accumulation part 170 accumulated with the entangled parts 190 is created. Further, fluffs generated from the fiber bundle during the separation processing are formed as a fluff accumulation 180 near the entanglement accumulation part 170 at the time of the separation processing.

Thereafter, by penetrating the separation means 200 into the fiber bundle 100 again, the not-separation-processed section 120 is created and a partially separated fiber bundle 130 or 140 is formed in which the separation-processed sections 110 and the not-separation-processed sections 120 are disposed alternately along the lengthwise direction of the fiber bundle 100. In the partially separated fiber bundle, the content of the not-separation-processed sections 120 is set to 3% or more and 50% or less. The content of the not-separation-processed sections 120 is defined as the rate of the total generation length of the not-separation-processed sections 120 in a unit length of the fiber bundle 100. If the content of the not-separation-processed sections 120 is less than 3%, the process stability of the separation processing is deteriorated, the flowability, at the time when the partially separated fiber bundle is cut and the cut bundles are sprayed and used as an intermediate base material of fiber bundles of discontinuous fibers, becomes poor. If the content of the not-separation-processed sections 120 exceeds 50%, the mechanical properties of a molded article molded using it decrease.

Further, as the length of each section, the length of the separation-processed section 110 is preferably 30 mm or more and 1,500 mm or less, and the length of the not-separation-processed section 120 is preferably 1 mm or more and 150 mm or less.

The running speed of the fiber bundle 100 is preferably a stable speed with little fluctuation, more preferably a constant speed.

The separation means 200 is not particularly limited as long as the desired result can be achieved, and it is preferable to have a shape like a sharp shape such as a metal needle or a thin plate. As the separation means 200, it is preferred that a plurality of separation means 200 are provided in the width direction of the fiber bundle 100 which is performed with the separation processing, and the number of separation means 200 can be arbitrarily selected depending upon the number of single fibers F forming the fiber bundle 100 to be carried out with the separation processing. It is preferred that the number of separation means 200 is (F/10,000−1) or more and less than (F/50−1) with respect to the width direction of the fiber bundle 100. If it is less than (F/10,000−1), improvements in mechanical properties are hardly exhibited when a reinforcing fiber composite material is made in a later step, and if it is (F/50−1) or more, there is a possibility of yarn breakage or fluffing during the separation processing.

The fiber bundle 100 is not particularly limited in fiber kind as long as it is a fiber bundle comprising a plurality of single fibers. In this connection, it is preferred to use reinforcing fibers and, in particular, the kind thereof is preferably at least one selected from the group consisting of carbon fibers, aramide fibers and glass fibers. These may be used solely, or two or more of them can be used together. Among those, carbon fibers are particularly preferable because it is possible to provide a composite material light in weight and excellent in strength. As the carbon fibers, any one of PAN type and pitch type may be used, and the average fiber diameter thereof is preferably 3 to 12 μm, and more preferably 6 to 9 μm.

In carbon fibers, usually, a fiber bundle obtained by bundling about 3,000 to 60,000 single fibers made of continuous fibers is supplied as a wound body (package) wound around a bobbin. Although it is preferred that the fiber bundle is untwisted, it is also possible to use a twisted strand, and it is applicable even if twisting occurs during conveyance. There is no restriction on the number of single fibers, and when a so-called large tow having a large number of single fibers is used, since the price per unit weight of the fiber bundle is inexpensive, as the number of single fibers increases, the cost of the final product can be reduced, and such a condition is preferred. Further, as a large tow, a so-called doubling form in which fiber bundles are wound together in a form of one bundle may be employed.

When reinforcing fibers are used, it is preferred that they are surface treated for the purpose of improving the adhesive property with a matrix resin used when made to a reinforcing fiber composite material. As the method of the surface treatment, there are an electrolytic treatment, an ozone treatment, an ultraviolet treatment and the like. Further, a sizing agent may be applied for the purpose of preventing fluffing of the reinforcing fibers, improving convergence property of the reinforcing fiber strand, improving adhesive property with the matrix resin, and the like. As the sizing agent, though not particularly limited, a compound having a functional group such as an epoxy group, a urethane group, an amino group, a carboxyl group or the like can be used, and as such a compound, one type or a combination of two or more types may be used.

The fiber bundle is preferably in a state of being bundled in advance. “The state of being bundled in advance” indicates, for example, a state in which the single fibers forming the fiber bundle are bundled by entanglement with each other, a state in which the fibers are converged by a sizing agent applied to the fiber bundle, or a state in which the fibers are converged by twist generated in a process of manufacturing the fiber bundle.

This disclosure is not limited to when the fiber bundle travels and, as shown in FIGS. 4(A) and 4(B), a method may be also employed wherein the separation means 200 is penetrated into the fiber bundle 100 being in a stationary state (arrow (1)), then, while the separation means 200 is traveled along the fiber bundle 100 (arrow (2)), the separation-processed part 150 is created, and thereafter, the separation means 200 is removed (arrow (3)). Thereafter, as shown in FIG. 4(A), the separation means 200 may be returned to the original position (arrow (4)) after the fiber bundle 100 having been in a stationary state is moved by a constant distance at timings shown by arrows (3) and (4), or as shown in FIG. 4(B), without moving the fiber bundle 100, the separation means 200 may be traveled until it passes through the entanglement accumulation part 120 (arrow (4)).

When the fiber bundle 100 is subjected to separation processing while it is moved by a constant distance, as shown in FIG. 4(B) or FIG. 5(A), it is preferred to control a separation processing time during being penetrated with the separation means 200 (the time of operation indicated by arrow (2)) and a time from being removed with the separation means 200 to being penetrated again into the fiber bundle (the time of operation indicated by arrows (3), (4) and (1)).

In this case, the moving direction of the separation means 200 is the repetition of (1) to (4) in the figure.

Further, when the fiber bundle 100 is not moved and the separation processing is performed while moving the separation means 200 until the separation means 200 passes through the entanglement accumulation part 170, as shown in FIG. 5(B), it is preferred to control a separation processing time during being penetrated with the separation means 200 (the time of operation indicated by arrow (2) or arrow (6)) and a time from being removed with the separation means 200 to being penetrated again into the fiber bundle (the time of operation indicated by arrows (3), (4) and (5) or by arrows (3), (4) and (1)).

Also in this case, the moving direction of the separation means 200 is the repetition of (1) to (4) in the figure.

Thus, by the separation means 200, the separation-processed sections and the not-separated-processed sections are alternatively formed, and a partially separated fiber bundle is produced so that the not-separation-processed sections become within a predetermined range of ratio with respect to the total length of the fiber bundle.

Depending upon the entanglement state of single fibers forming the fiber bundle 100, without securing a not-separation-processed section having an arbitrary length (for example, in FIGS. 3(A) and 3(B), after creating the separation-processed section 110, creating a next separation-processed part 150 with securing a not-separation-processed section 120 having a constant length), it is possible to restart separation processing subsequently from the vicinity of the terminal end portion of the separation-processed section. For example, as shown in FIG. 5(A), when the separation processing is performed while intermittently moving the fiber bundle 100, after the separation means 200 performs the separation processing (arrow (2)), by setting the moving length of the fiber bundle 100 to be shorter than the length of the separation processing performed immediately before, the position (arrow (1)) where the separation means 200 is to be penetrated once again can be overlapped with the separation-processed section performed with the separation processing immediately before. On the other hand, as shown in FIG. 5(B), in carrying out the separation processing while moving the separation means 200 itself, after once removing the separation means 200 (arrow (3)), without moving it at a constant length (arrow (4)), the separation means 200 can be penetrated into the fiber bundle again (arrow (5)).

In such a separation processing, when a plurality of single fibers forming the fiber bundle 100 are interlaced with each other, since the single fibers are not substantially aligned in the fiber bundle, even if the separation means 200 is penetrated at the same position as the position where the separation processing has been already performed or as the position where the separation means 200 has been removed, in the width direction of the fiber bundle 100, the position to be penetrated is easily shifted with respect to the single fiber level, and the separation processed state (gap) is not continued from the separation-processed section formed immediately before and they can exist as separation-processed sections different from each other.

The length of the separation-processed section 110 obtained per one separation processing is preferably 30 mm or more and less than 1,500 mm, although it depends upon the entanglement state of single fibers of the fiber bundle performed with the separation processing. If it is less than 30 mm, the effect according to the separation processing is insufficient, and if it is 1,500 mm or more, depending upon the reinforcing fiber bundle, there is a possibility of occurrence of yarn breakage or fluffing.

Further, when a plurality of separation means 200 are provided, it is also possible to provide a plurality of alternately formed separation-processed sections and not-separation-processed sections approximately parallel to each other with respect to the width direction of the fiber bundle. In this case, as aforementioned, it is possible to arbitrarily dispose a plurality of projected parts 210 by arranging a plurality of separation means 200 in parallel, staggeringly, in shifted phases or the like.

Furthermore, each of the plurality of projected parts 210 can also be controlled independently. Although the details will be described later, it is also preferred that the individual projected parts 210 independently perform separation processing by the time required for the separation processing or the pressing force detected by the projected part 210.

In any case, the fiber bundle is unwound from an unwinding device (not shown) or the like disposed on the upstream side in the fiber bundle traveling direction for unwinding the fiber bundle. As the unwinding direction of the fiber bundle, although a laterally unwinding system for pulling out in a direction perpendicular to the axis of rotation of a bobbin and a longitudinally unwinding system for pulling out in the same direction as the axis of rotation of the bobbin (paper tube) are considered, the laterally unwinding system is preferred in consideration that in that system there are few unwinding twists.

Further, with respect to the installation posture of the bobbin at the time of unwinding, it can be installed in an arbitrary direction. In particular, when, in a state where the bobbin is pierced through the creel, the end surface of the bobbin on the side not being the creel rotation shaft fixed surface is directed in a direction other than the horizontal direction, it is preferred that the fiber bundle is held in a state where a constant tension is applied to the fiber bundle. When there is no constant tension in the fiber bundle, it is considered that the fiber bundle falls from and is separated from a package (a winding body in which the fiber bundle is wound on the bobbin), or that a fiber bundle separated from the package winds around the creel rotation shaft, whereby unwinding becomes difficult.

Further, as a method of fixing the rotation shaft of the unwound package, in addition to the method of using a creel, a surface unwinding method is also applicable wherein a package is placed on two rollers arranged in parallel with each other at a state in parallel with the two parallel rollers, and the package is rolled on the arranged rollers to unwind a fiber bundle.

Further, in unwinding using a creel, a method of applying a tension to the unwound fiber bundle by applying a brake to the creel by putting a belt around the creel, fixing one end of the belt, and hanging the weight or pulling with a spring at the other end or the like, is considered. In this case, varying the braking force depending upon the winding diameter is effective as means for stabilizing the tension.

Furthermore, for adjustment of the number of single fibers after separation processing, a method of widening the fiber bundle and a method of adjustment by a pitch of a plurality of separation means arranged in the width direction of the fiber bundle can be employed. By making the pitch of the separation means smaller and providing a larger number of separation means in the width direction of the fiber bundle, it becomes possible to perform a so-called thin bundle separation processing into thin bundles each having fewer single fibers. Further, it is also possible to adjust the number of single fibers even by widening the fiber bundle before separation processing and applying separation processing to the widened fiber bundle with a larger number of separation means without narrowing the pitch of the separation means.

The term “widening” means a processing of expanding the width of the fiber bundle 100. The widening method is not particularly restricted, and it is preferred to use a vibration widening method of passing through a vibration roll, an air widening method of blowing compressed air or the like.

The separation-processed part 150 is formed by repeating penetration and removal of the separation means 200. At that time, it is preferred to set the timing of penetrating again by the time passed after removing the separation means 200. Further, also it is preferred to set the timing of removing again by the time passed after penetrating the separation means 200. By setting the timing of penetrating and/or removing by time, it becomes possible to create the separation-processed section 110 and the not-separation-processed section 120 at predetermined distance intervals, and it also becomes possible to arbitrarily determine the ratio between the separation-processed section 110 and the not-separation-processed section 120. Further, although the predetermined time intervals may be always the same, it is also possible to change the intervals in accordance with circumstances such as increasing or shortening the intervals depending upon the distance at which the separation processing has been progressed, or changing the intervals depending upon the state of the fiber bundle at respective times, for example, shortening the predetermined time intervals when there is little fluffing or entanglement of single fibers in the original fiber bundle or the like.

When the separation means 200 is penetrated into the fiber bundle 100, since the created entangled part 190 continues to press the projected part 210 in accordance with the progress of the separation processing, the separation means 200 receives a pressing force from the entangled part 190.

As aforementioned, a plurality of single fibers are not substantially aligned in the fiber bundle 100 but in most portions they are interlaced with each other at the single fiber level and, further, in the lengthwise direction of the fiber bundle 100, there is a possibility where there exist a portion with many entanglements and a portion with few entanglements. In the portion with many entanglements of single fibers, the rise of the pressing force at the time of separation processing becomes fast, and conversely, in the portion with few entanglements of single fibers, the rise of the pressing force becomes slow. Therefore, it is preferred that the separation means 200 is provided with a pressing force detection means for detecting a pressing force from the fiber bundle 100.

Further, since the tension of the fiber bundle 100 may change before and after the separation means 200, at least one tension detection means for detecting the tension of the fiber bundle 100 may be provided in the vicinity of the separation means 200, or a plurality of them may be provided and a difference in tension may be calculated. These means for detecting the pressing force, the tension and the tension difference may be provided individually, or may be provided in a form of any combination thereof. The tension detection means for detecting the tension is disposed preferably 10 to 1,000 mm apart from the separation means 200 in at least one of the front and rear of the fiber bundle 100 along the lengthwise direction of the fiber bundle 100.

It is preferred that the removal of the separation means 200 is controlled in accordance with each detected value of these pressing force, tension and tension difference. It is further preferred to control to remove the separation means 200 when the detected value exceeds an arbitrarily set upper limit value accompanying the rise of the detected value. In the pressing force and the tension, it is preferred to set the upper limit value to 0.01 to 1 N/mm, and in the tension difference to 0.01 to 0.8 N/mm. The upper limit value may be varied within a range of ±10% depending upon the state of the fiber bundle. The unit (N/mm) of the pressing force, the tension and the tension difference indicates force acting per the width of the fiber bundle 100.

If lower than the range of the upper limit value of the pressing force, the tension or the tension difference, because immediately after penetrating the separation means 200 the pressing force, the tension or the tension difference reaches a value to be removed with the separation means 200, a sufficient separation processing distance cannot be obtained, the separation-processed section 110 becomes too short, and therefore, the fiber bundle performed with separation processing tried to be obtained cannot be obtained. On the other hand, if exceeding the range of the upper limit value, because after penetrating the separation means 200 cutting of the single fibers in the fiber bundle 100 increases before the pressing force, the tension or the tension difference reaches a value to be removed with the separation means 200, defects such as projecting of the fiber bundle having been performed with separation processing in a shape like a split end or increase of generated fluffs, are likely to occur. The projected split end may be wrapped around a roll being served to the conveyance, or the fluffs are accumulated on a drive roll to cause slipping in the fiber bundle and the like, and thus, a conveyance failure tends to be caused.

Different from when the timing of removal of the separation means 200 is controlled with time, in detecting the pressing force, the tension and the tension difference, because the separation means 200 is removed before a force enough to cut the fiber bundle 100 is applied during the separation processing, an unreasonable force is not applied to the fiber bundle 100, and continuous separation processing becomes possible.

Furthermore, to obtain the fiber bundle 100 having a long separation-processed section 110 and a stable shape of the entanglement accumulation part 170 in the lengthwise direction, while suppressing the occurrence of branching or fluffing like a partial cutting of the fiber bundle 100, it is preferred that the pressing force is controlled to 0.04 to 0.4 N/mm, the tension is controlled to 0.02 to 0.2 N/mm, and the tension difference is controlled to 0.05 to 0.5 N/mm.

It is also preferred to provide an imaging means for detecting the presence of a twist of the fiber bundle 100 in a range of 10 to 1,000 mm in at least one of the front and rear of the fiber bundle 100 along the lengthwise direction of the fiber bundle 100 from the separation means 200 having been penetrated into the fiber bundle 100. By this imaging, the position of the twist is specified beforehand, and it is controlled to not penetrate the separation means 200 into the twist, thereby making it possible to prevent a mistake in penetration. Further, by removing the separation means 200 when the twist approaches the penetrated separation means 200, that is, by controlling to not penetrate the separation means 200 into the twist, it is possible to prevent narrowing in width of the fiber bundle 100. A mistake in penetration means that the separation means 200 is penetrated into the twist, the fiber bundle 100 is only pushed and moved in the penetrating direction of the separation means 200, and the separation processing is not performed.

In a configuration in which a plurality of separation means 200 are present in the width direction of the fiber bundle 100 and are arranged at equal intervals, if the width of the fiber bundle 100 varies, because the number of single fibers having been performed with separation processing also varies, there is a possibility that a separation processing with a stable number of single fibers cannot be performed. Further, if the twist is forcibly performed with separation processing, because the fiber bundle 100 is cut at the single fiber level to generate a large amount of fluffs, the shape of the entanglement accumulation part 170 in which the entangled parts 190 are accumulated becomes large. If the large entanglement accumulation part 170 is left, it is easily caught by the fiber bundle 100 unwound from the roll.

When the twist of the fiber bundle 100 is detected, other than the control to not penetrate the separation means 200 into the twist, the traveling speed of the fiber bundle 100 may be changed. Concretely, after the twist is detected, the traveling speed of the fiber bundle 100 is increased at the timing when the separation means 200 is being removed from the fiber bundle 100 until the twist passes through the separation means 200, thereby efficiently avoiding the twist.

Further, an image calculation processing means for calculating the image obtained by the imaging means may be further provided, and a pressing force control means for controlling the pressing force of the separation means 200 based on the calculation result of the image calculation processing means may be further provided. For example, when the image calculation processing means detects a twist, it is possible to improve the passing ability of the twist when the separation means passes the twist. Concretely, it is preferred to detect the twist by the imaging means and control the separation means 200 so that the pressing force is decreased from just before the projected part 210 comes into contact with the detected twist to the time when the projected part 210 passes therethrough. When the twist is detected, it is preferred to reduce it to 0.01 to 0.8 time the upper limit value of the pressing force. When it is below this range, substantially the pressing force cannot be detected, it becomes difficult to control the pressing force, or it becomes necessary to enhance the detection accuracy of the control device itself. Further, when it exceeds this range, the frequency of the separation processing performed to the twist is increased and the fiber bundle becomes narrow.

The separation processing is performed in a nonuniform manner in the width direction or the lengthwise direction of the fiber bundle by the separation means. It is also possible to perform the nonuniform separation processing in both the width direction and the lengthwise direction.

FIGS. 6(A) and 6(B) show an example of a method of manufacturing a partially separated fiber bundle in which the nonuniform separation processing is performed in the width direction of the fiber bundle. For example, as shown in FIG. 6(B), using a separation means 200A provided with projected parts 210 arranged at nonuniform intervals with respect to the width direction of the fiber bundle 100, while travelling the fiber bundle 100, the separation means 200A provided with projected parts 210 arranged at nonuniform intervals is penetrated and removed, to obtain a partially separated fiber bundle 130A as shown in FIG. 6(A) in which separation-processed parts 150 are created in the separation-processed section 110 at nonuniform intervals in the width direction of the fiber bundle 100.

FIGS. 7(A) and 7(B) show an example of a method of manufacturing a partially separated fiber bundle in which the nonuniform separation processing is performed in the lengthwise direction of the fiber bundle. For example, as shown in FIG. 7(B), using separation means 200 a and the separation means 200 b in which projected parts 210 are arranged at uniform intervals with respect to the width direction of the fiber bundle 100 but the disposing intervals of the projected parts 210 are different from each other, while travelling the fiber bundle 100, by penetrating and removing one separation means 200 a and the other separation means 200 b sequentially into and from the fiber bundle 100 (that is, by removing one and then penetrating the other after exchanging one), as shown in FIG. 7(A), separation-processed parts 150 are created in the separation-processed section 110 at uniform intervals in the width direction of the fiber bundle 100, but the separation-processed parts 150 are created at different arrangement forms between the separation-processed sections 110 formed sequentially in the lengthwise direction of the fiber bundle 100. Namely, a partially separated fiber bundle 130B performed with a nonuniform separation processing in the lengthwise direction of the fiber bundle 100 is obtained.

In the method shown in FIGS. 7(A) and 7(B), instead of the separation means 200 a and the separation means 200 b, it is also possible to use a plurality of separation means each having projected parts 210 arranged at nonuniform intervals in the width direction of the fiber bundle 100 as shown in FIGS. 6(A) and 6(B) and the nonuniform intervals being different from each other. Namely, it is also possible to employ a method combining the method shown in FIGS. 6(A) and 6(B) and the method shown in FIGS. 7(A) and 7(B).

FIGS. 8(A) and 8(B) show another separation method, which shows an example of a method of manufacturing a partially separated fiber bundle in which a nonuniform separation processing is performed while the width of a fiber bundle is changed. In the illustrated example, the fiber bundle width control device 300 is used to perform a separation processing while changing (altering) the width of the fiber bundle 100 in the fiber bundle running direction. As the separation means 200C, in the illustrated example, a separation means having projected parts 210 arranged at uniform intervals in the width direction of the fiber bundle 100 is used. Although the separation processing is performed using this separation means 200C, as shown in FIG. 8(A), for example, if the separation means 200C is penetrated into the fiber bundle 100 at a state in which the width of the fiber bundle 100 is narrowed, projected parts 210 not to be penetrated into the fiber bundle 100 (for example, projected parts 210 present on both sides in the arrangement direction) are generated, and only the projected parts 210 present within the width of the fiber bundle 100 are penetrated into the fiber bundle 100 to create separation-processed parts 150, thereby forming the separation-processed section 110 having a predetermined length. If the separation means 200C is penetrated into the fiber bundle 100 at a state where the fiber bundle 100 is widened, as shown in the right part of FIG. 8(A), all of the 210 are penetrated into the fiber bundle 100 to create separation-processed parts 150, thereby forming the separation-processed section 110 having a predetermined length. As a result, different separation processings are performed between the fiber bundle portion narrowed in width of the fiber bundle 100 and the fiber bundle portion widened in width of the fiber bundle 100, and a partially separated fiber bundle 130C is obtained in which nonuniform separation processing has been performed in the lengthwise direction of the fiber bundle 100. The bundle width control unit 300 is not particularly restricted, for example, except the vibration widening method of passing through a vibrating roll and the air widening method of blowing compressed air as aforementioned, an applicable device such as a manner for directly regulating the width by pressing a width regulating guide having an operation area in the width direction of the fiber bundle onto the fiber bundle, can be employed.

Further, it is also preferred to use a rotating separation means rotatable as the separation means other than simply penetrating the separation means having the projected parts 210 into the fiber bundle 100. FIGS. 9(A) and 9(B) show examples of cases using rotating separation means, FIG. 9(A) shows an example of a rotating separation means for performing a nonuniform separation processing in the width direction of the fiber bundle, and FIG. 9(B) shows an example of a rotating separation means for performing a nonuniform separation processing in the lengthwise direction of the fiber bundle.

In the rotating separation means 220A shown in FIG. 9(A), a rotating shaft 240 orthogonal to the lengthwise direction of the fiber bundle is provided, and projected parts 210 are provided on the surface of the rotating shaft 240. More concretely, the projected part plates 210 a each having a shape α arranged with projected parts 210 at a constant interval in the circumferential direction are disposed at nonuniform intervals in the width direction of the fiber bundle which is a direction along the rotating shaft 240 (A-A′ and B-B′ direction in the figure) to constitute the rotating separation means 220A. Using this rotating separation means 220A, by performing the separation processing while traveling the fiber bundle and while intermittently rotating the rotating separation means 220A, in the fiber bundle, the separation-processed sections in each of which the intervals of the separation-processed parts are nonuniform in the width direction of the fiber bundle are generated sequentially in the lengthwise direction of the fiber bundle, thereby obtaining a partially separated fiber bundle performed with a nonuniform separation processing in the width direction of the fiber bundle.

In the rotation separating means 220B shown in FIG. 9(B), the projected part plates 210 a each having a shape α arranged with projected parts 210 at a relatively small constant interval in the circumferential direction and the projected part plates 210 b each having a shape β arranged with projected parts 210 at a relatively large constant interval in the circumferential direction are disposed alternately in the width direction of the fiber bundle which is a direction along the rotating shaft 240 (A-A′, B-B′, C-C′ and D-D′ direction in the figure) to constitute the rotating separation means 220B. Using this rotating separation means 220, by performing the separation processing while traveling the fiber bundle and while intermittently rotating the rotating separation means 220B, in the fiber bundle, the separation-processed sections in each of which the intervals of the separation-processed parts are relatively small in the width direction of the fiber bundle and the separation-processed sections in each of which the intervals of the separation-processed parts are relatively large in the width direction of the fiber bundle are generated alternately in the lengthwise direction of the fiber bundle, thereby obtaining a partially separated fiber bundle performed with a nonuniform separation processing in the lengthwise direction of the fiber bundle.

Although omitted in the figure, it is preferred that the rotating separation means 220A or 220B has a pressing force detection mechanism and a rotation stop position holding mechanism. Until a predetermined pressing force acts on the rotating separation means 220A or 220B by the both mechanisms, a predetermined rotation stop position is maintained and the separation processing is continued. When exceeding the predetermined pressing force, for example, when an entangled part 190 is caused at the position of the projected part 210, the rotating separation means 220A or 220B starts to rotate. Thereafter, the projected part 210 is removed from the fiber bundle, and the operation of penetrating the next projected part into the fiber bundle is performed. The shorter such a series of operations is, the shorter the not-separation-processed section becomes and, therefore, when it is attempted to increase the proportion of separation-processed sections, it is preferred to shorten these operations.

By arranging the projected parts 210 more in the rotating separation means 220A or 220B, it is possible to obtain a fiber bundle 100 with a high proportion of separation processing and to extend the life of the rotating separation means 220A or 220B. A fiber bundle with a high proportion of separation processing means a fiber bundle obtained by lengthening the separation-processed length within the fiber bundle, or a fiber bundle in which the frequency of occurrence of the separation-processed sections and the not-separation-processed sections is increased. Further, as the number of the projected parts 210 provided in one rotating separation means increases, the lifetime can be lengthened by reducing the frequency of contact of the projected parts 210 with the fiber bundle 100 and wear of the projected parts 210. As for the number of projected parts 210 to be provided, it is preferred to arrange 3 to 12 pieces at equal intervals on the disk-shaped outer edge, more preferably 4 to 8 pieces.

Thus, when attempting to obtain a fiber bundle with a stable fiber bundle width while giving priority to the proportion of separation processing and the life of the projected parts, it is preferred that the rotating separation means 220A or 220B has an imaging means for detecting a twist as aforementioned. Concretely, during normal operation until the imaging means detects the twist, the rotating separation means 220A or 220B intermittently repeats the rotation and the stop to perform the separation processing, and when the twist is detected, the rotational speed of the rotating separation means 220A or 220B is increased from the speed at the normal time and/or the stop time is shortened, thereby stabilizing the fiber bundle width.

It is also possible to control the stop time to zero, that is, to continue the rotation without stopping.

Further, other than the method of repeating the intermittent rotation and stopping of the rotating separation means 220A or 220B, the rotating separation means 220A or 220B may always continue to rotate. At that time, it is preferred to make either one of the traveling speed of the fiber bundle and the rotational speed of the rotating separation means 220A or 220B relatively faster or slower. When the speeds are the same, although separation-processed sections can be formed because the operation of penetrating/removing the projected part 210 into/from the fiber bundle is performed, since the separation processing operation acting on the fiber bundle is weak, there is a possibility that the separation processing may not be performed sufficiently. Further, when any one of the speeds is too fast or too slow, the number of times the fiber bundle and the projected parts 210 come in contact with each other increases, there is a possibility that yarn breakage may occur due to rubbing, which causes to be inferior in continuous productivity.

A reciprocating movement mechanism that performs the penetrating and removes the separation means 200 or the rotating separation means 220A or 220B by reciprocating movement of the separation means 200 or the rotating separation means 220A or 220B may be further provided. Further, it is also preferred to further provide a reciprocating movement mechanism for reciprocating the separation means 220 and the rotating separation means 220A or 220B along the feed direction of the fiber bundle. For the reciprocating movement mechanism, it is possible to use a linear motion actuator such as a compressed-air or electric cylinder or slider.

The number of separation-processed sections in using reinforcing fibers for fiber bundles is preferably at least (F/10,000−1) or more and less than (F/50−1) in a certain region in the width direction. F is the total number of single fibers forming the fiber bundle to be performed with separation processing. By providing the separation-processed sections controlled in number thereof at least at (F/10,000−1) or more in a certain region in the width direction, when the partially separated fiber bundle is cut to a predetermined length to be made into a discontinuous fiber reinforced composite material, because the end portion of the reinforcing fiber bundle in the discontinuous fiber reinforced composite material is finely divided, a discontinuous fiber reinforced composite material having excellent mechanical properties can be obtained. Further, when the partially separated fiber bundle is used as continuous fibers without cutting it, when a reinforcing fiber composite material is made by impregnating a resin or the like thereinto in a later process, a starting point for resin impregnation into the reinforcing fiber bundle is made from a region included with many separation-processed sections, the molding time can be shortened and voids and the like in the reinforcing fiber composite material can be reduced. By controlling the number of separation-processed sections to less than (F/50−1), the obtained partially separated fiber bundle becomes hard to cause yarn breakage, and the decrease of mechanical properties when made into a fiber-reinforced composite material can be suppressed.

Next, the fiber-reinforced resin molding material will be explained.

The fiber-reinforced resin molding material contains a reinforcing fiber mat obtained by cutting/spraying the above-described partially separated fiber bundle and a matrix resin.

The average fiber length of the cut-off partially separated fiber bundle is preferably 5 to 100 mm, and more preferably 10 to 80 mm. The distribution of the fiber length may be a distribution of a single-kind fiber length or a mixture of two or more kinds.

Further, the matrix resin is not particularly restricted, and any of a thermosetting resin and a thermoplastic resin can be used, and it can be appropriately selected within a range that does not greatly deteriorate the mechanical properties as a molded article. For example, in a thermosetting resin, a vinyl ester resin, an epoxy resin, an unsaturated polyester resin, a phenol resin, an epoxy acrylate resin, a urethane acrylate resin, a phenoxy resin, an alkyd resin, a urethane resin, a maleimide resin, a cyanate resin, or the like can be used. Among them, any one of vinyl ester resin, epoxy resin, unsaturated polyester resin, phenol resin, or a mixture thereof is preferred. Further, in a thermoplastic resin, polyolefin-based resins such as polyethylene resin and polypropylene resin, polyamide-based resins such as nylon 6 resin and nylon 6,6 resin, polyester-based resins such as polyethylene terephthalate resin and polybutylene terephthalate resin, a polyphenylene sulfide resin, a polyether ketone resin, a polyether sulfone resin, an aromatic polyamide resin or the like can be used. Among them, any one of a polyamide resin, a polypropylene resin and a polyphenylene sulfide resin is preferred. A thermosetting resin can be used more preferably from the viewpoint of impregnating property of the matrix resin and applicability to the impregnating step.

FIG. 10 shows a method of producing a fiber-reinforced resin molding material according to an example. In FIG. 10, symbol 1 denotes the whole of a process of producing a fiber-reinforced resin molding material containing at least a reinforcing fiber mat and a matrix resin, wherein the production process 1 comprises at least a partial separation step [A] 2 to obtain a partially separated fiber bundle 7 in which separation-processed parts separated into a plurality of bundles so that the numbers of single fibers of the divided fiber bundles in the separation-processed sections become nonuniform and not-separation-processed parts are alternately formed along the lengthwise direction of the reinforcing fiber bundle comprising a plurality of single fibers, a matting step [B] 3 to obtain a reinforcing fiber mat 10 by cutting the partially separated fiber bundle 7 and spraying the cut bundles, and a resin impregnation step [C] 4 in which the reinforcing fiber mat 10 is impregnated with a matrix resin (thermosetting resin 11 in this example).

A reinforcing fiber bundle 6 composed of reinforcing fibers 6 a of a plurality of single fibers fed out from a plurality of creels 5 is supplied to the partial separation step [A] 2, partial separation processing is carried out in the step 2 as aforementioned, the partially separated fiber bundle 7 is manufactured.

The manufactured partially separated fiber bundle 7 is subsequently (continuously) supplied to the matting step [B] 3, where it is cut into discontinuous fiber bundles by a cutter unit 8 in the step 3 and, thereafter, the cut bundles are sprayed through a spraying mechanism 9, for example, on a belt 13 being circulated, such that a reinforcing fiber mat 10 is formed. This reinforcing fiber mat 10 is impregnated with a thermosetting resin 11 as a matrix resin and, in this example, the resin impregnation in the resin impregnation step [C] 4 is accelerated such that the reinforcing fiber mat 10 and the supplied thermosetting resin 11 to be impregnated are nipped films 12 sequentially supplied to both upper and lower sides of the reinforcing fiber mat 10, and at the nipped state, they are pressed, for example, between a plurality of resin impregnation rollers 14. The reinforcing fiber mat 10 impregnated with the matrix resin is folded as shown in the figure or wound as a continuous sheet-like fiber-reinforced resin molding material 15, and thus, a series of continuous fiber-reinforced resin molding material production process 1 is completed. The fiber-reinforced resin molding material 15 is produced, for example, as a sheet molding compound (SMC).

Thus, since first a partially separated fiber bundle 7 is manufactured, the partially separated fiber bundle 7 is cut and sprayed to prepare a reinforcing fiber mat 10 derived from the partially separated fiber bundle, and thereinto the matrix resin 11 is impregnated to obtain the fiber-reinforced resin molding material 15, when cutting and spraying the partially separated fiber bundle 7 to prepare the reinforcing fiber mat 10 as an intermediate base material of fiber bundles of discontinuous fibers, it becomes possible to make thin fiber bundles and thick fiber bundles present at a mixed condition within a range of an optimum ratio, and in the fiber-reinforced resin molding material 15 impregnated with matrix resin 11 thereinto, it becomes possible to exhibit the flowability during molding and the mechanical properties of a molded article at a good balance. In particular, in the manufacturing process of the partially separated fiber bundle 7, as described above, the fiber bundle can be stably slit continuously, and the partially separated fiber bundle 7 in an optimum form can be easily and efficiently produced. Especially, even in a fiber bundle containing twist or a fiber bundle of a large tow having a large number of single fibers, a continuous slit processing becomes possible without worrying about exchange life of a rotary blade. In addition, a continuous slit processing of an inexpensive large tow becomes possible, whereby it may become possible to reduce the material cost and production cost of a finally molded article.

From the viewpoint that it is possible to produce a desired fiber-reinforced resin molding material 15 efficiently, smoothly, and with excellent productivity in the above-described production process 1 of the fiber-reinforced resin molding material, an example is shown as a preferred example wherein a series of the steps [A] to [C] are carried out continuously in one process, but it is not necessary to continuously carry out the series of the steps [A] to [C] in one process, for example, the partially separated fiber bundle obtained through the step [A] may be wound up once and then subjected to the step [B].

Further, when cutting the partially separated fiber bundle 7 in the matting step [B] 3 as shown in FIG. 10, it is also preferred to cut the partially separated fiber bundle 7 at an angle θ (0<θ<90°) with respect to the lengthwise direction of the fiber bundle 7. For example, as shown in FIG. 11, with a cutting blade 8 a inclined at an angle θ (0<θ<90°) with respect to the lengthwise direction of the partially separated fiber bundle 7 (running direction of the fiber bundle in the figure), the partially separated fiber bundle 7 is cut. In this way, the chance of the cutting line by the cutting blade 8 a to extend over the separation-processed section 150 and the not-separation-processed part 180 increases, and when cutting the partially separated fiber bundle 7 to make the fiber bundle of the discontinuous fibers, because the chance that the discontinuous fiber bundle is formed only from the not-separation-processed part 180 decreases, it becomes possible to form a mat comprising discontinuous fiber bundles with a thinner size. In a fiber-reinforced resin molding material using such a mat, it becomes possible to particularly improve the mechanical properties of a molded article.

EXAMPLES

Next, examples and comparative examples will be explained. This disclosure is not limited in any way to the examples and comparative examples.

Raw Material Fiber Bundle [A-1]:

A continuous carbon fiber bundle (“PANEX (registered trademark) 35”, supplied by ZOLTEK CORPORATION) having a fiber diameter of 7.2 μm, a tensile modulus of elasticity of 240 GPa, and a number of single fibers of 50,000 was used.

Matrix Resin [M-1]:

A resin compound prepared by sufficiently mixing and stirring 100 parts by weight of a vinyl ester resin (“DELAKEN (registered trademark) 790”, supplied by Dow. Chemical Co., Ltd.), 1 part by weight of tert-butyl peroxybenzoate (“PERBUTYL (registered trademark) Z”, supplied by NOF CORPORATION) as a curing agent, 4 parts by weight of magnesium oxide (MgO #40, supplied by Kyowa Chemical Industry Co., Ltd.) as a thickener, and 2 parts by weight of zinc stearate (SZ-2000, supplied by Sakai Chemical Industry Co., Ltd.) was used.

Evaluation Method of Mechanical Property

After placing the fiber-reinforced resin molding material in the central part of a flat metal mold (50% in terms of charge rate), it was cured under a pressure of 10 MPa by a pressurizing type press machine at a condition of about 140° C. for 5 minutes to obtain a flat plate of 300×400 mm. Five test pieces (total 10 pieces) each having a size of 100×25×1.6 mm were cut out from the obtained flat plate from the respective directions of 0° and 90° when the lengthwise direction of the flat plate was set to 0°, and based on JIS K7074 (1988), the measurement was carried out. As the mechanical properties, a flexural strength, a flexural modulus, and a CV value (%) of the flexural modulus were determined (CV: coefficient of variation).

Example 1

The fiber bundle [A-1] was unwound using a winder at a constant speed of 10 m/min, and the unwound fiber bundle was passed through a vibration widening roll vibrating in its axial direction at 10 Hz, and after the widening processing was performed, a widened fiber bundle widened to 60 mm was obtained by passing it through a width regulating roll having a width of 60 mm.

For the obtained widened fiber bundle, a separation means was prepared by setting iron plates for separation processing each having a projected shape with a thickness of 0.2 mm, a width of 3 mm and a height of 20 mm in parallel with respect to the width direction of the reinforcing fiber bundle and at equal intervals of 1.3 mm for 20 plates and at equal intervals of 5.8 mm for 5 plates. Namely, this is supposed that the half of the widened fiber bundle widened to a width of 60 mm is divided into 20 parts and the remaining half is divided into 5 parts. This separation means was intermittently penetrated into and removed from the widened fiber bundle and was wound onto a bobbin to obtain a partially separated fiber bundle.

At this time, the separation means was penetrated into the widened fiber bundle traveling at a constant speed of 10 m/min for 3 seconds to create a separation-processed section, and the separation means was removed for 0.2 second, and it was penetrated again, and these operations were repeated.

The obtained partially separated fiber bundle was separated into the parts of the above-described supposed division number in the width direction of the fiber bundle in the separation-processed section, and at least at one end portion of at least one separation-processed section, an entanglement accumulation part accumulated with the entangled parts in which the single fibers were interlaced was formed. When the partially separated fiber bundle was manufactured by 1,500 m, the twist of the fibers existing in the fiber bundle passed through in the traveling direction when removing and penetrating the separation means, without causing yarn breakage and winding at all, and it was possible to carry out the separation processing with a stable width.

Further, five samples were cut out from the obtained partially separated fiber bundle each with a length of 1 m, and the lengths of the separation-processed sections and the not-separation-processed sections in each sample were measured and averaged to determine a distance between the separation-processed section and the not-separation-processed section. Further, the total sum of the not-separation-processed sections in the above-described measured samples was divided by the total length of 5 m of the samples, and the obtained value was obtained as the content of the partially separated fiber bundles. The obtained results are shown in Table 1.

Subsequently, the obtained partially separated fiber bundle was continuously inserted into a rotary cutter, and the fiber bundle was cut at a fiber length of 25 mm and the cut bundles were sprayed to be uniformly dispersed, whereby a discontinuous fiber nonwoven fabric whose fiber orientation is isotropic was obtained. The areal weight of the obtained discontinuous fiber nonwoven fabric was 1 kg/m².

The matrix resin [M-1] was uniformly applied to each of two polypropylene release films using a doctor blade to prepare two resin sheets. The discontinuous fiber nonwoven fabric obtained as described above was sandwiched between these two resin sheets from the upper and lower sides, and the resin was impregnated into the nonwoven fabric with rollers to obtain a sheet-like fiber-reinforced resin molding material. At that time, the application amount of the resin was adjusted at the stage of resin sheet preparation so that the weight content of reinforcing fibers in the fiber-reinforced resin molding material became 47%. With respect to the fiber-reinforced resin molding material obtained, the fiber-reinforced resin molding material was molded based on the aforementioned evaluation method of mechanical properties and the mechanical properties were evaluated. A series of evaluation results obtained are shown in Table 1.

Example 2

The evaluation was performed in the same manner as in Example 1 other than a condition where, as the separation means, two kinds of a separation means a in which iron plates for separation processing each having a projected shape with a thickness of 0.2 mm, a width of 3 mm and a height of 20 mm were set in parallel to each other with respect to the width direction of the reinforcing fiber bundle at equal intervals of 1.3 mm, and a separation means b in which the iron plates for separation processing were set in parallel to each other with respect to the width direction of the reinforcing fiber bundle at equal intervals of 5.8 mm, were prepared, and for the widened fiber bundle widened to 60 mm traveling at a constant speed of 10 m/min, the separation means a was penetrated thereinto for 3 seconds to create a separation-processed section a, the separation means a was removed therefrom for 0.2 second, subsequently the separation means b was penetrated to create a separation-processed section b, the separation means b was removed therefrom for 0.2 second, and the operation of again penetrating the separation means a repeatedly was performed. A series of evaluation results obtained are shown in Table 1.

Example 3

The evaluation was performed in the same manner as in Example 2 other than a condition where without once winding the obtained partially separated fiber bundle, it was continuously inserted into a rotary cutter, and then, it was subjected to a matting step and a resin impregnation step. A series of evaluation results obtained are shown in Table 1.

Example 4

The evaluation was performed in the same manner as in Example 3 other than a condition where when the partially separated fiber bundle was cut by the rotary cutter, the cutting angle was set at 15° with respect to the lengthwise direction of the fibers. A series of evaluation results obtained are shown in Table 1.

Comparative Example 1

The evaluation was performed in the same manner as in Example 1 other than a condition where the fiber bundle [A-1] was cut and sprayed without being performed with widening processing and separation processing to obtain a discontinuous fiber nonwoven fabric. A series of evaluation results obtained are shown in Table 2.

Comparative Example 2

For the widened fiber bundle using the fiber bundle [A-1] travelling at a constant speed of 10 m/min, the same separation means as that in Example 1 was always kept in a penetrated state, and a continuously separated fiber bundle performed with a continuous separation processing was manufactured. In the obtained continuously separated fiber bundle, the separation-processed section was formed continuously in the lengthwise direction of the fibers, at a part a quality deterioration due to remarkable fluffing was observed, the twists of fibers existed in the fiber bundle were accumulated at a position of the separation means, a partial yarn breakage occurred, and it was impossible to continuously perform the separation processing.

TABLE 1 Example Unit 1 2 3 4 Used raw Reinforcing fibers — [A-1] [A-1] [A-1] [A-1] material Matrix resin — [M-1] [M-1] [M-1] [M-1] Partially Content of not- % 6 6 6 6 separated separation-processed fiber sections bundle Length of separation- mm 500 500 500 500 processed section Length of not- mm 33 33 33 33 separation-processed section Mechanical Flexural strength MPa 420 415 420 450 properties FLexural modulus GPa 25 26 25 29 CV of flexural % 8 10 9 7 modulus

TABLE 2 Comparative Example Unit 1 2 Used raw Reinforcing fibers — [A-1] [A-1] material Matrix resin — [M-1] [M-1] Partially Content of not-separation- % 100 0 separated processed sections fiber bundle Length of separation- mm — — processed section Length of not-separation- mm — — processed section Mechanical Flexural strength MPa 290 — properties FLexural modulus GPa  22 — CV of flexural modulus %  25 —

We confirmed that in Examples 1 to 4 excellent mechanical properties (flexural strength and modulus) and low variation thereof were both exhibited. In particular, in Example 4, by setting the cutting angle θ of the partially separated fiber bundle at 0°<θ<90°, it was possible to suppress the stress concentration at the end of the fiber bundle and the formation of the resin rich portion in the molded article, and to achieve further high strength and low variation. Further, in this result, although an explicit method of confirming the flowability was not employed, the flat plates molded for the evaluation of the physical properties all had high surface smoothness and no resin spots where the resins coagulated were also present. Furthermore, no chipping was observed, and they were completely filled flat plates.

On the other hand, in Comparative Example 1, because the separation processing was not performed, any fiber bundle in the molded article was thick, and stress concentration occurred at the end portion of the fiber bundle, and the decrease in mechanical properties and the increase in variation were observed. Further, resin spots were observed in the flat plate, and it was recognized also from the appearance that the uniformity was low.

INDUSTRIAL APPLICABILITY

Our methods can be applied to any fiber bundle in which it is desired to separate a fiber bundle composed of a plurality of single fibers into thin bundles each having a less number of single fibers and, in particular, our methods are suitable for when the partially separated fiber bundle is cut/sprayed and made into an intermediate substrate of fiber bundles of discontinuous fibers to manufacture a molding material used for molding a composite material, it is possible to control thin fiber bundles and thick fiber bundles at a controlled distribution state and exhibit the flowability during molding and the mechanical properties of a molded article at a good balance. 

1.-21. (canceled)
 22. A partially separated fiber bundle in which separation-processed sections and not-separation-processed sections are alternately formed along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed sections being divided into a plurality of divided fiber bundles, the partially separated fiber bundle being characterized in that the numbers of single fibers of the divided fiber bundles in the separation-processed section are nonuniform.
 23. The partially separated fiber bundle according to claim 22, wherein the numbers of single fibers of the divided fiber bundles are nonuniform in a width direction of the fiber bundle.
 24. The partially separated fiber bundle according to claim 22, wherein the numbers of single fibers of the divided fiber bundles are nonuniform in the lengthwise direction of the fiber bundle.
 25. The partially separated fiber bundle according to claim 22, wherein the length of each of the separation-processed sections is 30 mm or more and 1,500 mm or less.
 26. The partially separated fiber bundle according to claim 22, wherein the length of each of the not-separation-processed sections is 1 mm or more and 150 mm or less.
 27. The partially separated fiber bundle according to claim 22, wherein the content of the not-separated-processed sections contained in the partially separated fiber bundle is 3% or more and 50% or less.
 28. A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers travels along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a separation means in which the intervals of the projected parts are nonuniform in the width direction of the fiber bundle is penetrated, and separation processing is performed in a nonuniform manner with respect to the width direction of the fiber bundle.
 29. A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers travels along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that a plurality of separation means having different intervals of the projected parts are penetrated in order in the lengthwise direction of the fiber bundle, and separation processing is performed in a nonuniform manner with respect to the lengthwise direction of the fiber bundle.
 30. A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers travels along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that the separation means is penetrated while the width of the fiber bundle is varied, and separation processing is performed in a nonuniform manner with respect to the lengthwise direction of the fiber bundle.
 31. A method of producing a partially separated fiber bundle wherein, while a fiber bundle comprising a plurality of single fibers travels along the lengthwise direction of the fiber bundle, a separation means provided with a plurality of projected parts is penetrated into the fiber bundle to create a separation-processed part, and entangled parts, where the single fibers are interlaced, are formed at contact parts with the projected parts in at least one separation-processed part, thereafter the separation means is removed from the fiber bundle, and after passing through an entanglement accumulation part including the entangled parts, the separation means is penetrated again into the fiber bundle, characterized in that the separation means is penetrated while the width of the fiber bundle is varied, and separation processing is performed in a nonuniform manner with respect to the lengthwise direction of the fiber bundle, wherein the nonuniform separation processing with respect to the lengthwise direction of the fiber bundle is performed together with the nonuniform separation processing according to claim
 28. 32. The method according to claim 28, wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, and the separation means is removed from the fiber bundle accompanying an increase of the pressing force.
 33. The method according to claim 28, wherein the presence of a twist of the fiber bundle in a range of 10 to 1,000 mm from the separation means having been penetrated into the fiber bundle in at least one of the front and rear of the fiber bundle along the lengthwise direction of the fiber bundle is detected by an imaging means.
 34. The method according to claim 33, wherein a pressing force acting on the projected parts per a width of the fiber bundle at the contact parts is detected, a twist is detected by the imaging means, and the separation means is controlled so that the pressing force is reduced until the projected parts are passed through the twist from immediately before being contacted with the twist.
 35. The method according to claim 28, wherein a plurality of the projected parts are independently controllable.
 36. The method according to claim 28, wherein the separation means has a rotational shaft orthogonal to the lengthwise direction of the fiber bundle, and the projected parts are provided on a surface of the rotational shaft.
 37. A fiber-reinforced resin molding material comprising a reinforcing fiber mat obtained by cutting/spraying the partially separated fiber bundle according to claim 22 and a matrix resin.
 38. The fiber-reinforced resin molding material according to claim 37, wherein the matrix resin is a thermosetting resin.
 39. The fiber-reinforced resin molding material according to claim 37, wherein the fiber-reinforced resin molding material is a sheet molding compound.
 40. A method of producing the fiber-reinforced resin molding material according to claim 37, comprising at least steps [A] to [C]: [A] a partial separation step of obtaining a partially separated fiber bundle by alternately forming separation-processed parts and not-separation-processed parts along a lengthwise direction of a fiber bundle comprising a plurality of single fibers, each of the separation-processed parts being separated so that the numbers of single fibers of divided fiber bundles in a separation-processed section are nonuniform; [B] a matting step of cutting the partially separated fiber bundle and spraying the cut bundles to obtain a reinforcing fiber mat; and [C] a resin impregnation step of impregnating a matrix resin into the reinforcing fiber mat.
 41. The method according to claim 40, wherein at least the steps [A] to [C] are carried out continuously in a single process.
 42. The method according to claim 40, wherein in the step [B], the partially separated fiber bundle is cut at an angle θ (0<θ<90°) with respect to the lengthwise direction thereof. 